Lecture 4 - Introduction to Protozoology

    Cards (44)

    • Protozoans are an extremely diverse assortment of unicellular eukaryotes.
    • Protozoa
      • Lack a cell wall
      • Have at least one motile stage in life cycle
      • Most ingest their food
    • Autotrophs - contain chloroplasts.
    • Heterotrophs - absorb organic molecules or
      ingest larger food particles.
      • Phagocytosis
    • Mixotrophs - combine photosynthesis and heterotrophic nutrition.
    • Free-living and symbiotic species.
      • Mutualistic – benefits both.
      • Commensalistic – one benefits, the other is neutral.
      • Parasitic – one benefits at a cost to the other.
    • Others use ameboid movement to get around.
      • A pseudopod is extended forward, followed by the rest of the organism.
    • Pseudopodia are extensions of the cell cytoplasm used for locomotion.
      • Nucleus – contains DNA.
      • Mitochondria – organelle used in energy production.
      • Golgi – part of the secretory system of the ER.
      • Plastids – organelles containing photosynthetic pigments.
      • Extrusomes – organelles that extrude something from the cell.
    • Holozoic feeders, or phagotrophs, ingest particles of food.
      • Food vacuole – the membrane-bound vesicle containing the food.
    • Contractile vacuoles fill with fluid and then
      expel the fluid outside the cell.
      • Function in osmoregulation.
    • Fission is the cell multiplication process in protozoa.
      • Binary fission – one individual splits into two equal sized individuals.
      • Budding – progeny cell much smaller than parent.
      • Multiple fission – multiple nuclear divisions followed by multiple cytoplasmic divisions producing several offspring.
    • Many protists are able to survive harsh
      conditions through the formation of cysts, dormant forms with resistant outer coverings and a shutdown of metabolism.
    • Opisthokonta is a very large clade characterized by a combination of flattened mitochondrial cristae and one posterior flagellum on flagellated cells.
    • The clade Stramenopila includes several groups of heterotrophs as well as certain groups of algae.
    • The clade Viridiplantae contains unicellular
      and multicellular green algae, bryophytes and vascular plants.
    • Phylum Chlorophyta – single celled algae colonial forms.
    • Phylum Euglenozoa is a diverse clade that includes
      predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites. Kinetoplastids & Euglenids.
    • Euglenids have one or two flagella that emerge from a pocket at one end of the cell.
    • Kinetoplastids have a single, large mitochondrion that contains an organized mass of DNA called a
      kinetoplast.
    • Phylum Retortamonada includes commensal and parasitic unicells.
      • Lack mitochondria & Golgi
    • Diplomonads have two nuclei and multiple flagella.
      • Giardia
      • Are adapted to anaerobic environments.
      • Lack plastids.
      • Lack mitochondria but may have mitochondrial genes in the nucleus.
    • Members of the clade Alveolata have membrane-
      bounded sacs (alveoli) just under the plasma
      membrane.
    • Members of the phylum Ciliophora use cilia to move and feed.
    • Ciliates are a large, varied group of protists.
    • All ciliates have a kinety system made up of the cilia, kinetosomes and other fibrils.
    • Alveolata - Ciliates
      Many have structures that can be expelled such as trichocysts and toxicysts.
    • Suctorians – ciliates that lose cilia as adults, grow a stalk and become sessile.
      • Use tubelike tentacles for feeding.
    • Symbiotic ciliates – some commensal, others parasitic.
    • Free-living ciliates – may be swimmers, or sessile.
      • Stentor, Vorticella, Paramecium
    • Paramecium, as well as many other protists, reproduce asexually by binary fission.
    • Conjugation is a sexual process that produces genetic variation.
    • Conjugation is separate from reproduction
      which generally occurs by binary fission.
    • Phylum Dinoflagellata is a diverse group of aquatic photoautotrophs and heterotrophs.
      • Abundant in both marine and freshwater phytoplankton.
    • Apicomplexans are parasites of animals and some cause serious human diseases.
    • Have a non-photosynthetic plastid, the apicoplast.
    • Parabasalids move by means of flagella and an undulating part of the plasma membrane.
      • This clade may have diverged from the main eukaryotic clade very early.
      • Trichomonas
    • Amebas are found in fresh and salt water as well as moist soil.
      • feeds by wrapping a pseudopod around its food – phagocytosis.
    • Nonactinopod amebas include amebas that form lobopodia, filipodia or rhizopodia.
      • Mostly heterotrophic and actively seek and consume bacteria and other protists.
    See similar decks